Device for locking the platen of typewriters



Oct. 17, 1933. I H KRAUS 1,931,199

DEVICE FOR LOOKING THE IPLATEN OF TYPEWRITERS Filed July 25, 1929 Patented Oct. 17, 1933 PATENT OFFICE DEVICE FOR LOCKING THE PLATEN OF TYPEWRITERS Hans Kraus, Vienna, Austria, assigncr, by mesne assignments, to Heindl- & Petters, Vienna, Austria, a company of Austria Application July 25, 1929, Serial No. 380,979, and

in Austria August 17, 1928 9Glaims. (11197-141) This invention relates to a device for locking the platen of a typewriter after a predetermined number of lines has been typed on'the paper.

A locking device of this kind is already known in which the platen is secured against rotation by a pawl engaging a ratchet wheel. However this arrangement possesses the drawback, that it cannot be attached to any make of typewriter, because the pawl is mounted on a lever and provided with a long shaft carrying a nipper-lever. The latter is readily bent and thus placed out of operation.

According to the present invention the locking device is arranged in a casing which is secured to the platen-carriage, and an eccentrically disposed shaft passes out of the casing and is coupled with the shaft of the platen. A pinion, mounted in the casing on the shaft, is adapted to be placed in mesh with a small toothed wheel, which can be engaged and disengaged from outside and meshes with a toothed drum, arranged on the inner wall of the casing, the said small toothed wheel moving the said toothed drum up to an adjustable stop and thereby locking the feeding device of the platen.

The drum, provided with an internal toothed wheel, can be used as the locking device, the said drurnbeing returned into the initial position by a toothed return-feed wheel, which 80 meshes with the said internal toothed wheel and is provided with a spring which is placed in tension when feeding forward the drum.

The casing-like locking device is provided with a stop, which can be set according to the number of lines intended to be typed, in order to prevent the feed of the platen on reaching the last line and place in operation the automatic carriage return mechanism, whereby it is rendered impossible to again type in the'last line owing to inadvertance. Whenever the said stop cc-operates with a pin provided on the toothed drum, the latter is locked, and further the entire casing and the lever for operating the automatic carriage return mechanism are rotated. In view thereof the engagement between the platen-carriage and its feed device will be disengaged until the locking device is disengaged. Further the said stop is connected with an adjusting ring provided with a scale for setting the said ring with respect to a sign, which is arranged on the casing. If desired a window may be provided inorder to render visible the number 01' lines already typed, which is indicated by the sign. For this object the periphery of the toothed drum is divided and marked according to the number of lines.

One mode of carrying out the present invention is illustrated by way of example on the accompanying sheet of drawing in which:--

Figure 1 is a front view.

Figure 2 is a side view.

Figure 3 is a sectional view of the locking device. 1

Figures 4 and 5 illustrate the locking mecha- 1 nism in two extreme positions.

Fig. 6 shows the arrangement of the toothed wheels.

The shaft 10, mounted in the bottom 1 of the casing, can be coupled with the shaft 20 of the 7,0 platen by means of an adjustable chuck 21. The pinion 11 carried by the shaft 10 meshes with the toothed wheel 12 rotatably mounted on a shaft 22 if the shaft 22 which is eccentrlcally journaled in the casing, has been adjusted into the position shown in Figs. 4 and 6 by means of 'theknob 28. The toothed wheel 12 then engages the internal toothing 3 carried by the drum 4 which, by means of the toothed wheel 12 rotatable on the shaft 22, is rotated clock- 80,

wise to such an extent until its pin 5 engages with the stop 6 carried by the casing 1. The shaft 23 of the wheel 15 is subjected to the action of the spiral spring 16 suitably supported within the casing.

A double-armed lever 24 is pivotally mounted in the centre of the top part 2'7 of the casing and a knob 28, arranged on the long arm of. the said lever, projects beyond the casing-cover 29 and is adjustable in a slot (Figs. 1 and 2). 9 The casing cover 29 is secured to the top part 27 of the casing by screws or the like.

In the disengaged position of the platen and locking device, the end 25 of the lever 24 comes within the range of a cranked plate spring 38, which secures the lever 24 in this position and prevents. the return of the latter by means of the spring 16. The spring 38 is fixed to the top part 27 by means of a screw 39.

The short arm of the lever 24 is connected by way of a link 30 to a cam 26 arranged on the shaft 22. The cam 26 is located in the space between the top part 2'7 and the casing cover29 and in the operative position of the locking device rests on the inner wall of the top part 27 as shown in Fig. 4. One end of the spiral spring 16 is fixed to the boss of the lever 24. The said spring has the tendency to move the latter and, by way of the cam 26, alsothe toothed intermediate wheel 12 into the position shown in Fig. 4.

A lockingring 31 is fixed to the plate 27 of the casing, and is provided on its periphery with a line-division or scale, which corresponds to the toothing, the latter being engaged by a handoperated spring-pawl 7'. An adjusting ring 32 is arranged freely rotatable between the bottom 1 and the plate 27 and carries the pawl '7 and is provided with a scale, corresponding to the linedivision and adjustable with respect to an indicator 32' provided on the bottom 1 of the casing. Tl'ie adjusting ring 32 is of T-shaped cross section and carries a stop 33, which extends into the path of movement of the pin 5 of the toothed drum 4 and thus limits the extent of movement of the latter. The extent of movement of the toothed drum 4, e. g. the number of lines already typed, can be read oif the line-division on the circumference of the toothed drum 4, appearing at the above indicator in a window as of the bottom 1 of the casing, the line-division on the circumference of the toothed drum 4 being visible through the said window. Whenever the number, corresponding to the figure set at the indicator appears in the window the platen is locked, sothat it cannot be turned after the set number of lines has been typed. For operating the automatic carriage return mechanism, the locking device, mounted on the shaft of the platen, is connected with the lever 36 operating said mechanism, for instance by way of a pin 8 of the casing-bottom 1 and a slot of the lever 36 (Figs. 1 and 2).

The lever 36 is the hand-operated lever which is arranged on any typewriter with automatic return of the paper carriage of known construction and is connected with the automatic carriage return mechanism in such manner that when the lever is operated the carriage is released and is' freely movable to return automatically into the initial position. According to the present invention this known lever 36 is provided with a slot through which passes the pin 8 of the locking device, forming the subjectmatter of the present invention, so that this looking device is connected with the lever 36. In view of this connection of the lever 36 with the said device, if the latter is disengaged by the knob 28,

the internal toothing 3 and consequently also the casing 1 are returned into the initial position by the spring 16. Thereby, in view of the rotation of the casing 1, the lever 36 connected with said casing is turned and the paper-carriage is automatically released and returned into its position for commencing the typing of a fresh line, while, however, the platen cannot be rotated, so that it cannot be set in position for typing a fresh line.

In order to adapt the locking device for platen-shafts of different diameters, the shaft 10 of the locking device is provided with an adjustable chuck 21 and further is removable together with the pinion 11 after removing a lid 37 from the bottom 1 of the casing.

Screws 35 serve for screwing together the bottom 1 and the top part 27 of the casing.

The locking device operates in the following manner:-

For instance, if it is desired to successively type on a number of sheets thirty lines only in order that all sheets show the same margin at the bottom, the number 30 of the adjusting ring 32 is set to the indicators after depressing the pawl '7. In this case the'figure 0 appears in the window 34 and indicates that the toothed drum 4 is disposed in the initial position. The

disengaged position of the device is shown in Fig. 5. The knob 23 is held in this position by the spring 33. If it is desired to move the knob 28 into the operative position as shown in Fig. 4, the engagement between the knob 28 and the spring 38 is interrupted by striking by hand the knob 28, whereby the spring 16 becomes operative and pulls up the knob into the position in shown in Fig. 2. Thereby the levers 25, 24, 30 and the cam 26 are moved from the position shown in Fig. 5 to the position shown in Fig. 4 so that the cam 26 now bears on the inner walls of the top part 27. In this position the cam 26 secures the eccentric 22 against rotation and also secures the wheels 11 and 12, which now mesh with each other against rotation in one direction, while the spring 16 prevents the rotation of said eccentric and thus the'wheels 11 and 12 in a reverse direction.' Now the wheel 12 cannot be rocked into the position shown in Fig. 5 so that the device cannot be disengaged due to the engagement between the wheels 11 and 12. The connection is established between the toothed drum 4 and the platen-shaft. The platen can be fed by hand from line to line under the control of the looking device. If the case arises that the platen and thus the paper has to be turned backward to a line already typed, the set to thirty lines is not disturbed in any way.

During the typing the toothed drum 4 and thus also its pin 5 always are fed forward according to the line-division until, after finally reaching the thirtieth line, the said pin cooperates with the stop 33 of the adjusting ring 32. In this position, the stop 33 obstructs the movement of the pin 5 and thus locks the mechanism, because the adjusting ring 32 is locked in the toothing of the ring 31 by means of the pawl 7'.

Further in View of the co-operation of both stops the toothed intermediate wheel 12 will be subjected to a pressure, which is further increased by the turning of the locking device necessary for engaging the automatic carriage return mechanism, so that, owing to the friction, the mechanism has to remain in the locked position until the locking mechanism is disengaged by moving the knob 28 into the out position.

In view of the co-operation of the two stops 5 and 33, the whole device has been slightly turned round the platen-shaft and thus the platen-carriage is automatically returned by way of the pin 8 and the lever 36.

The knob 28 is moved into the out position after the return of the platen-carriage, and therefore, during their return movement into the initial position, the locking mechanism and the lever 36 connected with it by the pin 8 again disengage the automatic carriage return mechanism after the paper-carriage has returned into its initial position. I

Thus the typist can add a further line only after he disengages the device.

In order to facilitate the removal of the sheet it is necessary to disengage the connection between the platen and the locking device. This is carried out by shifting the knob 28 into the out position whereby, by way of the lever 24 and the eccentric 22 (Fig. 5), the toothed intermediate wheel 12 is placed out of mesh with the pinion 11,

so that the toothed drum 4 is turned back by the spring-loaded toothed wheel 15 to such an extent, until its pin 5 reaches the stop 6 and thus the zero position.-

Now the locking device is disengaged from the platen and therefore the resilient lever 36 mayreturn to its initial position, whereby the said device participates in this return movement in view of the engagement by the pin 8. At the moment at which the resilient lever 36 reaches its initial position, the automatic carriage return mechanism again is interrupted and now the platen can be turned in the usual manner. When typing on similar sheets it is not necessary to again set the adjusting ring, but it is necessary only to engage, by means of the knob 28, the device after having inserted the sheet in the machine.

Eor correctly typing on certain sizes of sheets, for instance on postcards, reminders and so forth, the corresponding number can be marked on the adjusting ring in order to facilitate the quick adjustment.

I claim:----

1. Device for locking the platen of typewriters which is removably connected with the end of the platen-shaft carrying the knob for turning the platen, comprising in combination 2. casing, a shaft eccentrically disposed in and passing out of said casing for attachment to the platen-shaft, a pinion mounted on the casingshaft, a toothed intermediate wheel located in the casing and meshing with said pinion, an internally toothed drum in said casing, means for placing said intermediate wheel in and out of engagement'with said toothed drum, a pin secured to the latter, an adjustable stop on said casing projecting'into the path of movement of said pin of the rotatable drum and limiting the rotary feed of the platen, a pin fixed to the outside of the casing and engaging the feed disengaging lever of. the platen-carriage, the said adjustable stop on co-operating with the pin of the drum stopping the latter and thus the feed of the platen and further turning the entire looking device as well as the said feed disengaging lever about their respective pivots and thus disengaging the connection between the said lever and the platen-carriage.

2. Devic'eas claimed in claim 1, further com-' prising means for manually engaging and disengaging said intermediate wheel.

3. Device for locking the platen of typewriters which is removably connected with the end of the platen-shaft carryingthe knob for turning the platen, comprising in combination a a two-part casing, an adjusting ring provided .with a scale located between the two parts of said casing, a

shaft eccentrically disposed in and passing out of said casing for attachment to the platen-shaft, a pinion mounted on the casing-shaft, a toothed intermediate wheel located in the casing and meshing with said pinion, an internally toothed drum in said casing, means for placing said intermediate wheel in and out of engagement with said toothed drum, a pin secured to the latter, a stop on said adjusting ring projecting into the path of movement of said pin of the rotatable drum and limiting the rotary feed of the platen, a locking ring arranged in the casing, a springpawl mounted on said adjusting ring and engaging said locking ring for securing the adjusting ring in the adjusted position, a pin fixed to the outside of the casing and engaging the feed disengaging lever of the platen-carriage, the said stop of the adjusting ring on co-operating with the pin of the drum stopping the latter and thus the feed of the platen and further turning the entire locking device as well as the said feed disengaging lever about their respective pivots and thus disengaging the connection between the said lever and the platen carriage.

4. Device as claimed in claim 3, further comprising a scale on the circumference of the internally toothed drum, each division-mark of said scale indicating the number ofv the typed line-and a window in the casing of the locking device through which said scale is visible.

5. Device for locking the platen of typewriters which is removably connected with the end of the platen-shaft carrying the knob for turning the platen, comprising in combination a casing, a shaft eccentrically disposed in and passing out of said casing for attachment to the platen-shaft, a pinion mounted on the casing-shaft, a toothed intermediate wheel located in the casing and meshing with said pinion, an internally toothed drum in said casing, a double-armed coupling lever pivoted in the casing, one arm of said lever engaging said toothed drum, a slot in the casing of the device, a handle secured to the other leverarm for engaging and disengaging said intermediate wheel, a spring in the, casing co-operating with said lever and having the tendency to draw the latter into the coupling position, a pin secured to said toothed drum an adjusting ring in the casing, an adjustable stop on said adjusting ring projecting into the path of movement of said pin of the rotatable drum and :limitingthe rotary feed of the platen, a pin fixed to the outside of the casing and engaging the feed disengaging lever of the platen-carriage, the said adjustable stop on co-operating with the pin of the drum stopping the latter and thus the feed of the platen and further turning the entire locking device as well as the said feed disengaging lever about their respective pivots and thus disengaging the connection betweenthe said lever and the platencarriage.

6. Device as claimed in claim 5, further comprising a cranked plate-spring secured to the casing and engaging the coupling lever in the disengaged position of the platen and device to prevent a premature return of the lever.

'7. Device as claimed in claim 5, further comprising an eccentric mounted on the intermediate wheel and connected with the said double-armed coupling lever to facilitate the disengagement between the intermediate wheel and the pinion.

' 8. Device as claimed in claim 1, further comprising an adjustable chuck on the casing-shaft coupling the latterwith the platen-shaft.

9. Device as claimed in claim 1, further comprising an adjustable chuck on the casing-shaft coupling the latter with the platen shaft, and l 

